HDAC Profiling In Mantle Cell Lymphoma Unveils HDAC11 and HDAC10 as Potential Molecular Targets

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2506-2506
Author(s):  
Bijal D. Shah ◽  
Alejandro Villagra ◽  
Oscar Merino ◽  
Jennifer Rock-Klotz ◽  
Karrune Woan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
B Cells ◽  
B Lymphocytes ◽  
Cell Lines ◽  
Class Ii ◽  
Class I ◽  
Cell Cycle Analysis ◽  
Malignant Cells ◽  
Aberrant Expression

Abstract Abstract 2506 Background: Epigenetic changes in chromatin structure involving histone modifications have been recently implicated in the deregulated expression of critical genes in MCL, including cyclin D1 and some tumor suppressor genes. Special emphasis has been given therefore to the assessment of the therapeutic role of epigenetic modifiers in MCL. Among these, a family of compounds known as histone deacetylase inhibitors (HDI) display antitumor activity both in experimental models as well as in recently completed clinical trials in MCL patients. Given that aberrant expression of histone deacetylases (HDACs) has been shown to influence disease aggressiveness and response to treatment in several malignancies1,2,3, we seek to determine the expression of specific HDACs in human MCL. Methods: Expression of HDAC class I (HDAC1, 2, 3, 8), class II (HDAC4, 5, 6, 9, 10) and Class IV (HDAC11) was determined by quantitative real-time RT-PCR using specific HDAC primers in four human MCL cell lines (JEKO, Z138, MINO, SP53), primary malignant cells from lymph nodes of patients with MCL and in B-lymphocytes isolated from normal donors (Control). Protein expression of selected HDACs was evaluated by western blot. Knocking down of specific HDACs was performed using shRNAs lentiviruses targeting specific human HDAC sequences. Cell proliferation and cell cycle analysis of MCL cells lacking a specific HDAC were performed using standard techniques. Results: No significant differences in class I HDAC expression was found among normal B-lymphocytes, MCL cell lines and malignant B-cells from MCL patients. In contrast, the expression all class II HDACs, but HDAC9, was reduced in MCL cell lines and primary human MCL cells relative to normal B-cells. Of note, HDAC10 expression was consistently absent or significantly decreased in all MCL cell lines and primary MCL cells. Analysis of HDAC11 revealed interesting findings: increased expression of HDAC11 mRNA was observed in human MCL cell lines and primary human MCL cells, with the highest expression among two patients with the blastoid variant of MCL and the lowest expression in cells from two patients with a clinically indolent MCL. Next, we knocked-down HDAC11 in Z138 MCL cells and generated two stable clones (HDAC11KD) that displayed a slower cell proliferation relative to non-target shRNA control cells. Cell cycle analysis revealed that HDAC11KD clones are cycling at a significantly lower rate than control cells. Conclusion: HDAC11 over-expression in MCL seems to confer a proliferation/survival advantage to malignant cells. This finding provides a rationale to selectively disrupt this HDAC in MCL. Given that decreased HDAC10 expression is associated with a more aggressive behavior in other malignancies1, our findings of diminished HDAC10 expression in MCL warrant further investigation. Disclosures: Leonard: Hospira: Consultancy, Honoraria; Cell Therapeutics: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Honoraria; Biogen IDEC: Consultancy, Honoraria; Calistoga: Consultancy, Honoraria; Johnson and Johnson: Consultancy, Honoraria; EMD Serono: Consultancy, Honoraria; Sanofi Aventis: Consultancy, Honoraria; Millenium: Consultancy, Honoraria; Biotest: Consultancy, Honoraria; Cephalon: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Eisai: Consultancy, Honoraria; Cougar Biotechnology: Consultancy, Honoraria; Immunomedics: Honoraria; Genentech: Consultancy, Honoraria; Novartis: Consultancy, Honoraria.

Microrna-155 Controls The RB/E2F Axis In Normal and Malignant B Cells Via The Non-Canonical TGFβ1-SMAD5 Signaling Module

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 241-241 ◽  
Author(s):  
Daifeng Jiang ◽  
Ricardo Aguiar
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Germinal Center ◽  
Developmental Regulation ◽  
G1 Arrest ◽  
Malignant Cells ◽  
Germinal Center B Cells ◽  
In Cells

Abstract MicroRNA-155 (miR-155) plays pleiotropic roles in the biology of normal and malignant B cells. MiR-155 knockout (KO) mice have fewer germinal center B cells, while overexpression of this miRNA is associated with aggressive DLBCL. Although several miR-155 targets have been identified, a mechanism that unifies the features of loss and gain of miR-155 function in normal and malignant cells remains to be described. In B cells, TGFβ signals are suppressive indicating that deregulation of this pathway may interfere with the developmental regulation of lymphocytes and contribute to the pathogenesis of B cell malignancies. Earlier, we described the direct targeting of the transcription factor SMAD5 by miR-155, and uncovered the presence of non-canonical signaling model in B cell lymphomas whereby TGFβ1, a cytokine that typically activates SMAD2/3, phosphorylated SMAD5. Herein, we used the miR-155 KO mice and genetically modified DLBCL cell lines to investigate which downstream effectors of TGFβ signals are disrupted by the miR-155/SMAD5 interaction, thus shedding light on the phenotypes associates with miR-155 loss and gain of function. We confirmed the phosphorylation of SMAD5 by TGFβ1 in DLBCL cell lines, and demonstrated for the first time that this non-canonical signal is also present in untransformed normal mature B cells. We stably expressed miR-155 in the TGFβ1-responsive DLBCL cell lines Ly7, Ly18 and DHL5, and readily detected suppression of SMAD5, but not of other SMADs. TGFβ1 cytostatic activities include up-regulation of p15 and p21, which are primarily found in the context of SMAD2/3 activation. However, we found that stable expression of miR-155, and downregulation of SMAD5, significantly limited TGFβ1-dependent induction of both p15 and p21 in DLBCL. TGFβ1-mediated upregulation of p15 and p21 limits the activity of cyclin/CDK complexes, enriches for hypophosphorylated (active) RB, and promotes cell cycle arrest. We measured the effects of miR-155 in this process, and found that the accumulation of hypophosphorylated RB following TGFβ1 exposure was blunted in miR-155 expressing cells, resulting in an impaired G0/G1 arrest. The impact of miR-155 on TGFβ1 activity was also detectable by directly measuring the phosphorylation levels of RB’s Ser780 residue. Active pRB blocks cell cycle progression at least in part by binding to and inhibiting the E2F family of transcriptional regulators. Thus, we performed co-immunoprecipitation experiments and quantified the levels of RB-bound E2F1. In these assays, following TGFβ1 exposure we found a markedly decreased pRB-E2F1 complex formation in miR-155 expressing cells when compared to their controls. In agreement with these data, DLBCL cell lines expressing miR-155 displayed higher levels of free E2F1. Together, these data suggested the existence of a miR-155-SMAD5-p15/p21 axis that regulates TGFβ1 effects towards RB and E2F in DLBCL. To confirm the specific role of each component in this circuit, we used an RNAi strategy to transiently or stably knockdown (KD) SMAD5, p15 or p21 in our DLBCL models. In control RNAi cells, exposure to TGFβ1 led to decrease in RB phosphorylation, whereas these effects were abrogated upon KD of each of these genes, resulting in accumulation of hyperphosphorylated RB, a phenocopy of miR-155 expression. To define if the interplay between miR-155/SMAD5 and RB was also present in non-malignant cells, we purified mature B lymphocytes from miR-155 WT and KO mice. Examination of four pairs of mice, showed a higher expression of SMAD5 in cells from miR-155 KO than WT mice. In addition, TGFβ1-mediated suppression of phospho-RB was consistently more pronounced in miR-155 KO than in WT B cells, which resulted in a significantly higher G0/G1 arrest in cells lacking this miRNA. Of note, in absence of TGFβ1 there was no significant difference in cell cycle profile of mature B cells from miR-155 WT and KO mice. We concluded that an unrestrained TGFβ activity, secondary to SMAD5 upregulation, may help explain the deficient germinal center B cells formation found in miR-155 KO mice. Together, our findings demonstrate that miR-155 overexpression is a novel model for deregulation of the lymphomagenic RB/E2F axis, and define an unsuspected role for the non-canonical TGFβ1 activation of SMAD5 in the developmental regulation of mature B cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals MicroRNA-340 Induces Apoptosis and Inhibits Metastasis of Ovarian Cancer Cells by Inactivation of NF-κB1

2016 ◽  
Vol 38 (5) ◽  
pp. 1915-1927 ◽  
Author(s):  
Peiquan Li ◽  
Yuxin Sun ◽  
Qing Liu
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Cell Proliferation ◽  
Cell Lines ◽  
Mrna Level ◽  
Matrix Metalloproteinase 2 ◽  
Luciferase Reporter ◽  
Ovarian Cancer Cells ◽  
Aberrant Expression ◽  
Qrt Pcr

Aims: Aberrant expression of microRNA-340 (miR-340) has been frequently reported in some cancers excluding ovarian cancer (OC). The role and its molecular mechanism of miR-340 in OC have not been reported. Methods: Real-time PCR was performed to detect the expression of miR-340 in OC cell lines. MiR-340 mimic and negative control were transfected into OC cells and the effects of miR-340 on the cell proliferation, cell cycle, apoptosis and metastasis were investigated by Brdu-ELISA assay, flow cytometry, qRT-PCR, Transwell and ELISA assays. Furthermore, protein level of NF-κB1 was measured by Western blotting. Meanwhile, luciferase assays were performed to validate NF-κB1 as miR-340 target in OC cells. Results: In this study, we explored the effects of miR-340 overexpression on apoptosis, invasion and EMT in OC cells. The mRNA level of miR-340 in OC cell lines and tissues was evidently reduced. The miR-340 mimic was transiently transfected into OC cells using Lipofectamine™ 2000 reagent. Subsequently, the Brdu-ELISA results showed that introduction of miR-340 inhibited cell proliferation. Our data also demonstrated that miR-340 mimic arrested cell cycle progression and promoted apoptosis of OC cells. In addition, miR-340 overexpression could also inhibit invasion and EMT of OC cells. qRT-PCR were used to determined the expressions of matrix metalloproteinase-2 and -9 (MMP-2 and -9) in OC cells. Next, we found that NF-κB1 expression was evidently reduced by up-regulation of miR-340. Bioinformatics analysis predicted that the NF-κB1 was a potential target gene of miR-340. Luciferase reporter assay further confirmed that miR-340 could directly target the 3' UTR of NF-κB1. Moreover, overexpression of NF-κB1 in OC cells transfected with miR-340 mimic partially reversed the inhibitory of miR-340 mimic. Conclusion: miR-340 induced cell apoptosis and inhibited metastasis in OC cells by down-regulation of NF-κB1.

scholarly journals DYRK1A Is Required to Alleviate Replication Stress in KMT2A-Rearranged Acute Lymphoblastic Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 39-40
Author(s):  
Christian Hurtz ◽  
Martin P. Carroll ◽  
Sarah K Tasian ◽  
Gerald Wertheim ◽  
Rahul S. Bhansali ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
B Cells ◽  
High Risk ◽  
Fusion Protein ◽  
Cell Lines ◽  
Research Funding ◽  
Meta Analysis ◽  
Replication Stress ◽  
Pharmacologic Inhibition

Background: KMT2A-rearranged (R) ALL is associated with chemoresistance, relapse, and poor survival with a frequency of 75% in infants and 10% in children and adults with ALL. Current intensive multiagent chemotherapy regimens induce significant side effects, yet fail to cure many patients, demonstrating continued need for novel therapeutic approaches. We performed a kinome-wide CRISPR screen and identified DYRK1A as required for KMT2A-R ALL cell survival, but not in other high risk ALL genetic subtypes. DYRK1A is a member of the dual-specificity tyrosine phosphorylation-regulated kinase family and has been reported as a critical oncoprotein in a murine Down syndrome model of megakaryoblastic leukemia. DYRK1A negatively regulates cell proliferation and induces quiescence. Paradoxically, genetic deletion or pharmacological inhibition of DYRK1A upregulates the cell cycle regulator CCND3 and increased numbers of B cells in S-phase, yet also significantly reduces cell proliferation. The specific role of DYRK1A in ALL has not been reported. Results: We assessed the importance of DYRK1A deletion in a focused screen of 14 previously identified kinases. Meta-analysis of ChIP-Seq data from two KMT2A-AFF1 cell lines and a human KMT2A-Aff1-FLAG transduced ALL model demonstrated direct binding of both N-terminal (KMT2AN) and C-terminal (AFF1C) and the FLAG-tagged KMT2A-fusion to the DYRK1A promoter. To assess if KMT2A fusion directly regulates DYRK1A expression, we treated SEM cells with the menin-KMT2A disrupter MI-503 and identified that the KMT2A fusion protein is a positive regulator of DYRK1A. Pharmacologic inhibition of DYRK1A with EHT1610 demonstrated potent leukemic cell growth inhibition, demonstrating that DYRK1 could be a new therapeutic target in KMT2A-R ALL. To further elucidate the mechanism of DYRK1A function, we treated several KMT2A-R ALL cell lines in vitro with EHT1610, which resulted in accumulation of CCND3 as expected. In addition, we detected upregulation of the positive cell cycle regulator MYC and the replication stress response molecule CHK1. In a second experiment, we validated the upregulation of MYC and identified significant upregulation of the proapoptotic protein BIM. Strikingly, meta-analysis of gene expression data from Dyrk1a-deleted murine pre-B cells isolated from a conditional Dyrk1a knockout mouse model also demonstrated increased levels of MYC and CHK1, validating that the EHT1610 mediated upregulation of MYC or CHK1 is a specific effect induced by DYRK1A inhibition. Western blot analysis demonstrated that KMT2A-R ALL cell lines have constitutive activation of pH2AX. Based on these data, we hypothesize that DYRK1A-mediated upregulation of CCND3 and MYC forces the cells to proliferate, which significantly increases replication stress and causes apoptosis, as evident by upregulation of CHK1 and BIM. To test if targeting the interaction of BIM with BCL2 will have an increased apoptotic effect when combined with EHT1610, we treated two KMT2A-R ALL cell lines with increasing concentrations of EHT1610 and the BCL2 inhibitor venetoclax. Strikingly, we observed a synergistic effect with both drugs, suggesting that combining these inhibitors has superior anti-leukemic activity. Conclusions: DYRK1A and MYC are positively regulated by the KMT2A fusion protein in KMT2A-R ALL and negatively regulate each other. Pharmacologic inhibition of DYRK1A resulted in significant growth disadvantage of KMT2A-R ALL cells due to increased MYC and CHK1 proteins that induce replication stress. While further in vivo studies are needed, we predict that combining DYRK1A inhibition with venetoclax may be a novel precision medicine strategy for KMT2A-R ALL that is translatable to the clinic for patients with these high-risk leukemias. Disclosures Tasian: Gilead Sciences: Research Funding; Aleta Biotherapeutics: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Research Funding.

Electron microscopy analysis of degenerating pancreatic ß cells in transgenic mice expressing the MHC Class I antigen Dd

1990 ◽  
Vol 48 (3) ◽  
pp. 548-549
Author(s):  
T. A. Stewart ◽  
D. Liggitt ◽  
S. Pitts ◽  
L. Martin ◽  
M. Siegel ◽  
...  
Keyword(s):  
Type I Diabetes ◽  
Disease Process ◽  
Class Ii ◽  
Class I ◽  
Type I ◽  
Aberrant Expression ◽  
Mhc Molecules ◽  
Endogenous Insulin ◽  
Class Ii Mhc ◽  
Ifn Γ

Insulin-dependant (Type I) diabetes mellitus (IDDM) is a metabolic disorder resulting from the lack of endogenous insulin secretion. The disease is thought to result from the autoimmune mediated destruction of the insulin producing ß cells within the islets of Langerhans. The disease process is probably triggered by environmental agents, e.g. virus or chemical toxins on a background of genetic susceptibility associated with particular alleles within the major histocompatiblity complex (MHC). The relation between IDDM and the MHC locus has been reinforced by the demonstration of both class I and class II MHC proteins on the surface of ß cells from newly diagnosed patients as well as mounting evidence that IDDM has an autoimmune pathogenesis. In 1984, a series of observations were used to advance a hypothesis, in which it was suggested that aberrant expression of class II MHC molecules, perhaps induced by gamma-interferon (IFN γ) could present self antigens and initiate an autoimmune disease. We have tested some aspects of this model and demonstrated that expression of IFN γ by pancreatic ß cells can initiate an inflammatory destruction of both the islets and pancreas and does lead to IDDM.

Novel Anthraquinone Derivatives as Dual Inhibitors of Topoisomerase 2 and Casein Kinase 2: In Silico Studies, Synthesis and Biological Evaluation on Leukemic Cell Lines

2019 ◽  
Vol 18 (11) ◽  
pp. 1551-1562 ◽  
Author(s):  
Abbas Kabir ◽  
Kalpana Tilekar ◽  
Neha Upadhyay ◽  
C.S. Ramaa
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Cell Lines ◽  
Biological Evaluation ◽  
Casein Kinase ◽  
Casein Kinase 2 ◽  
Cell Cycle Analysis ◽  
Protein Targets ◽  
Topoisomerase 2 ◽  
Dual Inhibitors

Background: Cancer being a complex disease, single targeting agents remain unsuccessful. This calls for “multiple targeting”, wherein a single drug is so designed that it will modulate the activity of multiple protein targets. Topoisomerase 2 (Top2) helps in removing DNA tangles and super-coiling during cellular replication, Casein Kinase 2 (CK2) is involved in the phosphorylation of a multitude of protein targets. Thus, in the present work, we have tried to develop dual inhibitors of Top2 and CK2. Objective: With this view, in the present work, 2 human proteins, Top2 and CK2 have been targeted to achieve the anti-proliferative effects. Methods: Novel 1-acetylamidoanthraquinone (3a-3y) derivatives were designed, synthesized and their structures were elucidated by analytical and spectral characterization techniques (FTIR, 1H NMR, 13C NMR and Mass Spectroscopy). The synthesized compounds were then subjected to evaluation of cytotoxic potential by the Sulforhodamine B (SRB) protein assay, using HL60 and K562 cell lines. Ten compounds were analyzed for Top2, CK2 enzyme inhibitory potential. Further, top three compounds were subjected to cell cycle analysis. Results: The compounds 3a to 3c, 3e, 3f, 3i to 3p, 3t and 3x showed excellent cytotoxic activity to HL-60 cell line indicating their high anti-proliferative potential in AML. The compounds 3a to 3c, 3e, 3f, 3i to 3p and 3y have shown good to moderate activity on K-562 cell line. Compounds 3e, 3f, 3i, 3x and 3y were found more cytotoxic than standard doxorubicin. In cell cycle analysis, the cells (79-85%) were found to arrest in the G0/G1 phase. Conclusion: We have successfully designed, synthesized, purified and structurally characterized 1- acetylamidoanthraquinone derivatives. Even though our compounds need design optimization to further increase enzyme inhibition, their overall anti-proliferative effects were found to be encouraging.

scholarly journals Doxorubicin treatment modulates chemoresistance and affects the cell cycle in two canine mammary tumour cell lines

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Michela Levi ◽  
Roberta Salaroli ◽  
Federico Parenti ◽  
Raffaella De Maria ◽  
Augusta Zannoni ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Lines ◽  
Tumour Cell ◽  
S Phase ◽  
Mammary Tumour ◽  
Cancer Resistance ◽  
Neoplastic Cells ◽  
Canine Mammary Tumour ◽  
Tumour Cell Lines

Abstract Background Doxorubicin (DOX) is widely used in both human and veterinary oncology although the onset of multidrug resistance (MDR) in neoplastic cells often leads to chemotherapy failure. Better understanding of the cellular mechanisms that circumvent chemotherapy efficacy is paramount. The aim of this study was to investigate the response of two canine mammary tumour cell lines, CIPp from a primary tumour and CIPm, from its lymph node metastasis, to exposure to EC50(20h) DOX at 12, 24 and 48 h of treatment. We assessed the uptake and subcellular distribution of DOX, the expression and function of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP), two important MDR mediators. To better understand this phenomenon the effects of DOX on the cell cycle and Ki67 cell proliferation index and the expression of p53 and telomerase reverse transcriptase (TERT) were also evaluated by immunocytochemistry (ICC). Results Both cell lines were able to uptake DOX within the nucleus at 3 h treatment while at 48 h DOX was absent from the intracellular compartment (assessed by fluorescence microscope) in all the surviving cells. CIPm, originated from the metastatic tumour, were more efficient in extruding P-gp substrates. By ICC and qRT-PCR an overall increase in both P-gp and BCRP were observed at 48 h of EC50(20h) DOX treatment in both cell lines and were associated with a striking increase in the percentage of p53 and TERT expressing cells by ICC. The cell proliferation fraction was decreased at 48 h in both cell lines and cell cycle analysis showed a DOX-induced arrest in the S phase for CIPp, while CIPm had an increase in cellular death without arrest. Both cells lines were therefore composed by a fraction of cells sensible to DOX that underwent apoptosis/necrosis. Conclusions DOX administration results in interlinked modifications in the cellular population including a substantial effect on the cell cycle, in particular arrest in the S phase for CIPp and the selection of a subpopulation of neoplastic cells bearing MDR phenotype characterized by P-gp and BCRP expression, TERT activation, p53 accumulation and decrease in the proliferating fraction. Important information is given for understanding the dynamic and mechanisms of the onset of drug resistance in a neoplastic cell population.

scholarly journals Human Immunodeficiency Virus Type 1 Replication in the Absence of Integrase-Mediated DNA Recombination: Definition of Permissive and Nonpermissive T-Cell Lines

2001 ◽  
Vol 75 (17) ◽  
pp. 7944-7955 ◽  
Author(s):  
Noriko Nakajima ◽  
Richard Lu ◽  
Alan Engelman
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Lines ◽  
Dna Recombination ◽  
Cell Types ◽  
Class Ii ◽  
Class I ◽  
Immunodeficiency Virus ◽  
T Cell Lines ◽  
Hiv 1

ABSTRACT Functional retroviral integrase protein is thought to be essential for productive viral replication. Yet, previous studies differed on the extent to which integrase mutant viruses expressed human immunodeficiency virus type 1 (HIV-1) genes from unintegrated DNA. Although one reason for this difference was that class II integrase mutations pleiotropically affected the viral life cycle, another reason apparently depended on the identity of the infected cell. Here, we analyzed integrase mutant viral infectivities in a variety of cell types. Single-round infectivity of class I integration-specific mutant HIV-1 ranged from <0.03 to 0.3% of that of the wild type (WT) across four different T-cell lines. Based on this approximately 10-fold influence of cell type on mutant gene expression, we examined class I and class II mutant replication kinetics in seven different cell lines and two primary cell types. Unexpectedly, some cell lines supported productive class I mutant viral replication under conditions that restricted class II mutant growth. Cells were defined as permissive, semipermissive, or nonpermissive based on their ability to support the continual passage of class I integration-defective HIV-1. Mutant infectivity in semipermissive and permissive cells as quantified by 50% tissue culture infectious doses, however, was only 0.0006 to 0.005% of that of WT. Since the frequencies of mutant DNA recombination in these lines ranged from 0.023 to <0.093% of the WT, we conclude that productive replication in the absence of integrase function most likely required the illegitimate integration of HIV-1 into host chromosomes by cellular DNA recombination enzymes.

scholarly journals Nonmalignant T cells stimulate growth of T-cell lymphoma cells in the presence of bacterial toxins

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3325-3332 ◽  
Author(s):  
Anders Woetmann ◽  
Paola Lovato ◽  
Karsten W. Eriksen ◽  
Thorbjørn Krejsgaard ◽  
Tord Labuda ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Mhc Class Ii ◽  
Interleukin 2 ◽  
Class Ii ◽  
Bacterial Toxins ◽  
Dependent Manner ◽  
Malignant Cells ◽  
T Cell Lines

AbstractBacterial toxins including staphylococcal enterotoxins (SEs) have been implicated in the pathogenesis of cutaneous T-cell lymphomas (CTCLs). Here, we investigate SE-mediated interactions between nonmalignant T cells and malignant T-cell lines established from skin and blood of CTCL patients. The malignant CTCL cells express MHC class II molecules that are high-affinity receptors for SE. Although treatment with SE has no direct effect on the growth of the malignant CTCL cells, the SE-treated CTCL cells induce vigorous proliferation of the SE-responsive nonmalignant T cells. In turn, the nonmalignant T cells enhance proliferation of the malignant cells in an SE- and MHC class II–dependent manner. Furthermore, SE and, in addition, alloantigen presentation by malignant CTCL cells to irradiated nonmalignant CD4+ T-cell lines also enhance proliferation of the malignant cells. The growth-promoting effect depends on direct cell-cell contact and soluble factors such as interleukin-2. In conclusion, we demonstrate that SE triggers a bidirectional cross talk between nonmalignant T cells and malignant CTCL cells that promotes growth of the malignant cells. This represents a novel mechanism by which infections with SE-producing bacteria may contribute to pathogenesis of CTCL.

Mutation at autosomal loci of Chinese hamster ovary cells: involvement of a high-frequency event silencing two linked alleles

1983 ◽  
Vol 3 (7) ◽  
pp. 1172-1181
Author(s):  
W E Bradley
Keyword(s):  
Cell Lines ◽  
Chinese Hamster Ovary ◽  
High Frequency ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Low Frequency ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Ovary Cells

Two classes of cell lines heterozygous at the galactokinase (glk) locus have been isolated from Chinese hamster ovary cells. Class I, selected by plating nonmutagenized wild-type cells at low density in medium containing 2-deoxygalactose at a partially selective concentration, underwent subsequent mutation to the glk-/- genotype at a low frequency (approximately 10(-6) per cell), which was increased by mutagenesis. Class II heterozygotes, isolated by sib selection from mutagenized wild-type cells, had a higher spontaneous frequency of mutation to the homozygous state (approximately 10(-4) per cell), which was not affected by mutagenesis. About half of the glk-/- mutants derived from a class II heterozygote, but not the heterozygote itself, were functionally hemizygous at the syntenic thymidine kinase (tk) locus. Similarly, a tk+/- heterozygote with characteristics analogous to the class II glk+/- cell lines underwent high-frequency mutation to tk-/-, and most of these mutants, but not the tk+/- heterozygote, were functionally hemizygous at the glk locus. A model is proposed, similar to that for the mutational events at the adenine phosphoribosyl transferase locus (W. E. C. Bradley and D. Letovanec, Somatic Cell Genet. 8:51-66, 1982), of two different events, high and low frequency, being responsible for mutation at either of the linked loci tk and glk. The low-frequency event may be a point mutation, but the high-frequency event, in many instances, involves coordinated inactivation of a portion of a chromosome carrying the two linked alleles. Class II heterozygotes would be generated as a result of a low-frequency event at one allele, and class I heterozygotes would be generated by a high-frequency event. Supporting this model was the demonstration that all class I glk+/- lines examined were functionally hemizygous at tk.

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